This invention concerns functional fluorine-containing copolymers compositions and ionomers derived therefrom. The ionomers formed are useful in electrochemical applications such as batteries, fuel cells, in exchange membranes, sensors and the like.
International Publication number WO 99/45048 discloses substantially fluorinated but not perfluorinated ionomers and related ionic and nonionic monomers having pendant groups containing fluorosulfonyl methide or fluorosulfonyl imide derivatives and univalent metal salts thereof.
International Application No. PCT/US00/05,526 teaches a polymerization process for forming a copolymer comprising: co-polymerizing in aqueous emulsion one or more monomers selected from the group consisting of tetrafluoroethylene, trifluoroethylene, vinylidene fluoride, vinyl fluoride, ethylene, chlorotrifluoroethylene, hexafluoropropylene, hexafluoroisobutylene, perfluoromethyl vinyl ether, and perfluoroethyl vinyl ether with a fluorinated co-monomer having limited water solubility, said comonomer being dispersed in the form of droplets of a size of 10 microns or less, said polymerization process being conducted in the presence of a fluorinated surfactant and a free-radical initiator.
The present application copolymerizes the polymers produced by the above disclosures using a new method and produces co-polymers with novel properties.
The present invention provides for a polymer composition comprising a polymer, I, and the alkali metal sulfonate, ammonium sulfonate, sulfonic acid, and sulfonyl methide, both acid and salt, derivatives thereof, said polymer, I, 
comprising an amorphous segment, Ia, and a crystalline segment, Ib, wherein Rf is a linear or branched perfluoroalkenyl or perfluoroalkenyl ether diradical, the ratio u:v is in the range of 85:15 to 50:50, preferably 83:17 to 64:36, the ratio x:y is in the range of 100:0 to 87:13, preferably 100:0 to 93:7; said polymer being a copolymer of monomers IIa and IIb,
CF2xe2x95x90CH2xe2x80x83xe2x80x83IIa
CF2xe2x95x90CFxe2x80x94Oxe2x80x94Rfxe2x80x94SO2Fxe2x80x83xe2x80x83IIb
and wherein the ratio a:b is such that the overall concentration of monomer units derived from monomer IIb in said polymer is in the range of 6 mole % to 12 mole % said polymer being characterized in that the melting point thereof lies above the melting point of a fully random copolymer of monomers IIa and IIb of the same overall composition, and lies at least 5xc2x0 C. below the melting point of poly(vinylidene fluoride).
Further provided in the present invention is a process for forming a graft copolymer of the formula I, the process comprising
combining the monomer IIb at a concentration of 0.2 to 0.6 g/ml with water and a fluorosurfactant and agitating said combination to form an emulsion having a droplet size of no greater than 0.5 micrometers;
in a reaction vessel, combining in water said emulsion with monomer IIa at a first monomer concentration ratio and a free-radical initiator;
allowing said monomers to polymerize to form a first copolymer which may be amorphous or crystalline;
in a reaction vessel which may be the same or different, combining in water said first copolymer with an additional amount of said emulsion of monomer IIb and an additional amount of monomer IIa, at a second monomer concentration ratio, and an additional amount of a free radical initiator, and allowing said further amounts of monomer to polymerize to form a second copolymer, said second copolymer being crystalline if said first copolymer is amorphous and said second copolymer being amorphous if said first copolymer is crystalline;
wherein said first and second concentration ratios of monomer IIa to monomer IIb are in the range of 85:15 to 50:50 on a molar basis when the desired copolymer is amorphous, and in the range of 100:0 to 87:13 when the desired polymer is crystalline;
and, wherein the ratio of amorphous polymer concentration to crystalline polymer concentration is controlled so that the overall concentration of monomer units derived from monomer IIb is in the range of 6-12 mole %.
Further provided in the present invention is an electrochemical cell comprising an anode, a cathode, and a separator wherein at least one of said anode, cathode, or separator comprises the alkali sulfonate, ammonium sulfonate, sulfonic acid, or sulfonyl methide derivative of polymer I.